Another study of 45 tissue samples from Iranian patients (15 PTC, 15 paired normal and 15 goiter tissues) checked twelve genes (GAPDH, ACTB, HPRT1, TBP, B2M, PPIA, 18SrRNA, HMBS, GUSB, PGK1, RPLP0, and PGM1)26. Here, GAPDH is linked to goiter.